A
large button or coin, string, paper and a small piece of sticky
tape.

Instructions:

Cut 2
circles out of the paper to the exact same size as the button or
disc object. Cut a piece of string to approximately 50cm long then
attach one end to the disc using the tape. Glue a paper circle to
each side of the disc. Draw part of a complete picture on one side
and the corresponding part on the other. Wind the disk up then dangle
it from the string so that it quick unwinds, or flick it with your
finger to spin it. You will see the complete picture made up from
2 separate drawings.

Hints:

We have used the
classic 'Bird out of a cage' and "Bird in the cage' picture but you
should think of one of your own. You can also use writing to make a complete
sentence for example 'I' and 'You' on one side then 'Love' on the other.
Almost any picture can be broken into two parts but it helps if they each
mean something on there own as well as complete.

This project is know as an 'Optical
illusion' because it tricks your eyes into thinking there is a whole picture
when in reality you are looking at two separate pictures.